Designers of ICs use electronic design automation (EDA) tools, a category of computer aided design (CAD) tools, to create a functional circuit design, including a register transfer logic (RTL) representation of the functional circuit design, synthesize a “netlist” from the RTL representation, and implement a layout from the netlists. Synthesis of the netlist and implementation of the layout involve simulating the operation of the circuit and determining where cells should be placed and where interconnects that couple the cells together should be routed. EDA tools allow designers to construct a circuit, simulate its performance, estimate its power consumption and area and predict its yield using a computer and without requiring the costly and lengthy process of fabrication. EDA tools are indispensable for designing modern ICs, particularly very-large-scale integrated circuits (VSLICs). For this reason, EDA tools are in wide use.
Multiple EDA tools may be used when designing an IC. To manage the combination of the EDA tools that are used to design an IC, design flows are typically used. One type of design flow supports a hierarchical design methodology that allows designers to address problems on the physical side of the design process between logic synthesis and the implementation process. Through early analysis and floor planning, designers can apply physical constraints to assist in controlling the initial implementations of an IC design. Floor planning involves planning for the placement of various components, such as hierarchical design components, inside an IC. With a hierarchical design flow, EDA tools can allow a designer to reduce the number of iterations between running PAR (Place and Route) and then returning to the register transfer level (RTL) and synthesis thereof.
Current hierarchical design flows may be derived from two dominant design methodologies, top-down and bottom-up. The top-down and bottom-up methodologies are two extreme cases which may have more of a theoretical appeal than practical use. Typically, commercial CAD tools target the top-down design methodologies, while several in-house design teams utilize bottom-up methodologies. This can create a design gap since commercial CAD tools are unable to handle in-house designs smoothly. As such, improved hierarchical design flows would be useful in the art.